1. Field of the Invention
The present invention relates to a deflection yoke mounted to and used in a color cathode ray tube having an in-line arranged electron gun.
2. Description of the Related Art
According to a prior art described in Unexamined Patent Publication No. Hei 9(1997)-17355, variable resistors are respectively parallel-connected to correction coils wound around intermediate legs of a pair of E-shaped cores to compensate for or correct horizontal trapezoidal distortion (lateral trapezoidal distortion) developed in a cathode ray tube device by a variable resistor parallel-connected to vertical deflection coils and improve horizontal line misconvergences (V tilts) produced at screen upper and lower portions, among rasters displayed by side electron beams produced upon the correction.
In the prior art, however, the correction coils needed to be connected in series with the vertical deflection coils so as to generate barrel-type magnetic fields lying in a direction opposite to a vertical deflection direction. Thus, vertical deflection sensitivity was degraded.
An object of the present invention is to provide a deflection yoke provided with means capable of correcting horizontal line misconvergences produced at screen upper and lower portions, among rasters displayed by side beams, without changing horizontal trapezoidal distortion because degradation in vertical deflection sensitivity, which presents a problem in the prior art, does not take place and magnetic fields lying in a direction opposite to a vertical deflection direction are not produced, and a cathode ray tube device using the same.
Therefore, the present invention provides a deflection yoke comprising at least a vertical pair of saddle-type horizontal deflection coils, and a horizontal pair of saddle-type deflection coils, and mounted to and used in a color cathode ray tube having an in-line arranged electron gun, wherein a pair of sub-cores is provided on the electron gun side of the deflection yoke from side to side or up and down, at least one pair of correction coils is wound around each of the pair of sub-cores, the one pair of correction coils is connected in series with vertical deflection coils so that respective magnetic poles produced from the one pair of correction coils become identical to the pole of a cathode ray tube axis, and a variable resistor is connected in parallel with the one pair of correction coils to change a current that flows through the one pair of correction coils.
According to the deflection yoke of the present invention, a color cathode ray tube device can be obtained which is capable of independently correcting horizontal line misconvergences produced at screen upper and lower portions without virtually degrading vertical deflection sensitivity owing to the provision of the two pairs of correction coils in the above-described construction and which is free of horizontal trapezoidal distortion and the horizontal line misconvergences at the screen upper and lower portions by utilizing such correction in combination with the correction of the horizontal trapezoidal distortion produced by a variable resistor connected in parallel with the vertical deflection coils.